1. Field of the Invention
The invention relates to a variable slit width device to be applied to a spectroscope, particularly to an optical spectrum analyzer.
2. Related Art
A conventional variable slit width device for a spectroscope is now described with reference to FIGS. 4(A), 4(B), 4(C), and FIG. 5. In FIGS. 4(A), 4(B), and 4(C), depicted by 1 is a fixed part of the variable slit width device for a spectroscope. The fixed part 1 is fixed to such as an dispersible monochromator optical spectrum analyzer and other optical devices. A housing part 8 is fixed to the fixed part 1. The housing part 8 houses therein a slit part and a driving part for driving slits so as to open or close the slit part.
The slit part is now described. In FIGS. 4(A), 4(B), 4(C), depicted by 2 are slit defining members, which are parallel with two opposite surfaces of the housing part 8, and disposed in parallel with each other in a horizontal direction. Depicted by 24 is a blade face 24 of the slit defining members 2 which are parallel with two opposite faces of the housing part 8. 25 is also a blade face of the slit defining members 2 which is also disposed in the same manner as the blade face 24 but inclined relative to the two opposite faces of the housing part 8 by an angle of xcex8.
The slit defining members 2 are fixed to upper surfaces of a pair of slit holders 21. A pair of linear guides 3 (FIG. 5) having guide parts extending horizontally to the right and left are fixed to the upper and lower portions of the slit holders 21.
Referring to FIG. 5, a pair of guide shafts 37 engaging with the guide parts of the pair of linear guides 3 are perpendicularly fixed to two opposite surfaces of the housing part 8. As shown in FIG. 4(A), a switch 26 is provided for detecting open and close ends of the slit defining members 2, and a detection piece which is detected by the switch 26 is fixed to one of the slit holders 21.
A driving part for controlling and driving the slit part so as to close or open the slit part as set forth above will now be described. A pair of feed nuts 6 are disposed at the center between the pair of slit holders 21. The pair of the feed nuts 6 are respectively screwed on a closing screw 64. The closing screw 64 is fixedly attached to a single common shaft 65. The common shaft 65 is rotatably supported by bearings 66 fixed to the two opposite surfaces of the housing part 8.
Both the feed nuts 6 and the closing screw 64 are threaded respectively such that the feed nuts 6 are moved toward each other by the closing screw 64 when the common shaft 65 is rotated in one direction while the feed nuts 6 are moved away from each other by the closing screw 64 when the common shaft 65 is rotated in the other direction. Preload springs 63 are disposed between the two opposite surfaces of the housing part 8 and the feed nuts 6 for preloading the feed nuts 6 in a direction toward one another. The common shaft 65 is connected to the motor 7 via a coupling, and is driven by the motor 7.
With the variable slit width device for a spectroscope of the invention, the closing screw 64 fixed to the common shaft 65 is rotatably driven when the common shaft 65 is rotatably driven by the motor 7 via the coupling. When the closing screw 64 is rotated, the pair of slit holders 21 to which the feed nuts 6 threaded with the closing screw 64 are fixed are driven so as to be moved toward each other or moved away from each other while guided by the linear guides 3 and the pair of guide shafts 37. An interval between the slit defining members 2 is adjusted by adjusting the number of revolutions of the motor 7.
Another conventional variable slit width device for a spectroscope is described next with reference to FIGS. 6 (A), 6(B) and FIG. 7. The prior art in FIGS. 6 (A) and 6(B) relate to a slit width switching device for a spectroscope for selectively using slits from multiple fixed width slits depending on use conditions. A housing part a comprises a fixed part 1, a pair of flat plates 11 which are fixed perpendicularly to the fixed part 1 and disposed in parallel with each other, and a support rod 12. The housing part 8 houses therein slit parts set forth hereunder.
A shaft 9 is disposed on the pair of flat plates 11, and the shaft 9 is supported by bearings 91. A gear 92 is non-rotatably fixed to the shaft 9, and a thin circular plate 93 is positioned axially on the gear 92. A plurality of slits 2 having different widths are formed in the plane surface of the circular plate 93 on the same radius and regular angular intervals. A part of the gear 92 and a part of the circular plate 93 are arranged to protrude from the housing part 8.
The motor 7 is arranged in parallel with the shaft 9 and fixed to one of the flat plates 11, and a gear 92A meshing with the gear 92 is fixed to one shaft of the motor 7, while one revolution detection piece 74 which is detected by a switch 73 is fixed to the other shaft of the motor 7.
However, there was a problem in the variable slit width device for a spectroscope shown in FIG. 4 that it has not been used in a narrow space such as an optical path returning part such as a 2 path, 4 path, 8 path monochromator serving as an optical unit of the dispersible monochromator spectrum analyzer.
That is, even if the slits 2 are positioned in a narrow space such as an optical path returning part such as a 2 path, 4 path, 8 path monochromator, the entire variable slit width device for a spectroscope including the housing part 8 has to be carried in such a narrow space, which is however not practical. Further, there is another problem that the slit defining members 2 do not uniformly operate right and left, a width dimension and the central position in the width direction do not become in theoretical values owing to a manufacturing error of the right and left screws of the closing screw 64, thereby causing error.
Further, in the variable slit width device for a spectroscope as illustrated in FIGS. 6(A) and 6(B), the slits 2, which are formed in the circular plate 93 by disposing a part of the gear 92 and a part of the circular plate 93 so as to protrude from the housing part 8, can be used in a narrow space such as an optical path folding part of double path monochromator serving as an optical unit of the dispersible monochromator spectrum analyzer.
Accordingly, it is an object of the invention to provide a variable slit width device for a spectroscope which can be used in a narrow space such as an optical path folding part of a 2 path, 4 path, 8 path monochromator constituting a part of a dispersible monochromator spectrum analyzer, which is large in variable width with high accuracy.
To achieve the above object, the variable slit width device for a spectroscope of the invention comprises a fixed part fixed to an optical device, a pair of slit holders fixed to the fixed part, guide parts provided on the adjacent surfaces of the pair of slit holders and inclined by a given angle, slit defining members attached to the side surfaces of the pair of slit holders, linear guides having the guide parts provided at the lower surfaces thereof and extending vertically, the slit holders being fixed to the linear guides and guide rails being fitted to the guide parts of the linear guides, attachment plates for fixing the guide rails, springs for urging the pair of slit holders so as to be moved toward each other, and exclusive electrodes attached to the respective slit defining members for detecting the zero point of the interval between the slit defining members, the device additionally includes a pair of freely rotatable rotary parts for pressing inclined guide parts of the pair of slit holders, pressing parts for supporting the pair of rotary parts, linear guides having guide parts formed at the lower surfaces thereof and extending horizontally in a direction crossing with the guide rails at right angles, and the pressing parts being fixed to the linear guides, guide rails fitted to the guide parts of the linear guides, feed nuts fixed to the pressing parts, feed screws screwed with the feed nuts, bearings for rotatably supporting the feed screws, preload springs for preloading the feed nuts and the feed screws, a slit driving part for rotatably driving the feed screws, and a housing part for fixing thereto the guide rails, the bearings and the motor.
The variable slit width device for a spectroscope of the second aspect of the invention is characterized in that the slit defining members protrude from the slit holders and the slit driving part, the guide parts provided in the pair of slit holders are symmetrical with each other, and the slit defining members are inclined by an angle of xcex8 relative to a moving direction thereof when driven.